Many disposable cups have a frustoconical shape made from expanded foam, paper, or plastic with a construction having a lower closed end that is smaller than the upper open end. While this frustoconical cup construction is desirable from the standpoint of stackability, feel, and the ability to hold a greater volume than a cylindrical shape with the same size as the lower end of the cup, the frustoconical shape makes the containers susceptible to tipping when filled with liquid contents. This instability is a particular problem in moving vehicles where any change in momentum, both upon acceleration or deceleration, will cause the frustoconical cups to tip over and spill their contents unless positioned in a special holder. Even normal vehicle acceleration, deceleration upon braking, or cornering can produce enough change in momentum to tip over frustoconical cups.
The prior art discloses many disposable cups that require a holder for use. One such cup is disclosed by the U.S. Pat. No. 3,337,109 of Shumrak which discloses two embodiments of a cup holder. One of the embodiments has a cylindrical shape while the other has a frustoconical shape. Both of these cup holder embodiments are designed to support an associated cup just below an outwardly projecting rim at its upper open end and neither is disclosed as being stackable with the associated cups.
Other containers and container holders are disclosed by U.S. Pat. Nos.: 2,041,573 Meinecke; 2,235,502 Leppke; 2,576,725 Schoelles; 2,729,956 Gilbert; 3,207,461 Holzwarth et al; 3,246,786 Holley; and 3,954,178 Mason, Jr.